Moin Hispeed,
kopano-migration-pst, kopano-migration-imap, kopano-utils are as indipendent packages all found on kopano.io download package section community or supported edition. In your case most likely here (k4s is on debian 9): https://download.kopano.io/community/core:/core-8.6.80.1248_0%2B176-Debian_9.0-amd64.tar.gz.
It looks like apt-get install kopano-server-packages does not include these packages by default. I will add them into next release of k4s in case it is no coincidence with your nickname in other forums and you are still using synology migrating from z4h to k4s. -TosoBoso

Hi Tosoboso (me confused and surprised, “ja” we know each other from the synology-forum),

What happened here ;=)… yes I’m using still your Zarafa4h but I switch now to Ubuntu and Kopano Community version. I got it all running and up with certificate and everyhting. Now I need to migrate the emails from your z4h to Kopano. There are a few other reasons why I decided to use a dedicated virtual machine for this.
Your Synology version is of course still nice.

Back to my question. Fbartels and you are etlling me that this kopano-migration-pst is an independent package and is included but not by default with the installation of Kopano Core?
How I can I install kopano-migration-pst ?

Then I can only guess that you have since the original installation removed the custom repo that you have created above. The package is part of the current archive (and I am pretty sure it was back then as well)